Composite piston



T. P. cHAs'E COMPOSITE PISTON Jan. 7, 1'936.

origina; Filed April 15, 1929 Patented Jan. 7,1936

ENT OFFICE Theron P. Detroit, Mich., assignor, by

mesne assignments, toV General Motors Corporation, Detroit, D1w

Application pril 15, 1929, 'serial ifL .i Renewed May 27, 1933'v Mich., a corporationV of e icmm. (ciano-14) v This invention relates composite pistons.

By -4the term composite piston is meant .a piston of the type of which the head or the body is made of allight'metal or alloy, such as aluminumor an alloy of aluminum,- and the skirt or the bearing surfaces are made of a harder, wearresisting metal, such as iron or steel.

On account of the difference between the temperature coeiicients of expansion of the metals or' alloys ot which the head or the body and the 'num. and, as shown in the'drawing, consists of skirt or the bearing surfaces ofsuch pistons are f vmade incompositepistons asheretofore cona head 9 and a depending annular wall portion i which is integral with-the head. Adjacentthe open end of the body, thereare formed on the lannular wall portion` l0 diametrically opposed,

'structed, there has been either (1) -a tendency,4

for the parts to become loose and rattle at orgdinary atmospheric temperatures, or (2) a tend- 'ency for the piston to bind in the cylinder at ordinary operating temperatures. It is the principalv objectmf this invention to produce a com- I vention` which is shown in the accompanying ,v

tures, the skirt or bearing sleeve and the bodyV v portion will be spaced apart a short distance ra posite piston of which the parts will not become loose `and rattle at ordinary atmospheric temperatures and which will not bind in the cylinder at ordinary operating temperatures.

inwardly extending wrist pin bosses Il through which extend openings I2 which are coaxial with `lower end of the annular wall portion Y For,a more complete understanding of the 'na- I ture and the objects of my invention, reference is made to the following s pecication, in which isdescribed the preferred embodiment of my in- In the accompanying drawing:` Fig. 1 is a longitudinal cross-section, in' a plane ata right angle to the axis of the wrist pin bosses,

through a piston in which is embodiedmy 'infvention.

-1 Fig. 2 is ,a sectiont taken Eon the line 2-2 o! Fig. `1.

Fig'. 1.?.

Fig.' 4 is a lon Fig.'4 3 isa section takeni on V:the line ot gitudinal cross-section, through the skirtor bearing sleeve, takeninl a plane at y a right angle tothe axis of the ,wrist pin open'- ings.

on' the line 5-5 of Fig. 3 and showing,` on an exaggerated scale, the space between the skirt ory bearing sleeve and the body ofthe piston" at ordinary atmospheric temperatures.

In the accompanying drawing, the reference character 6 indicates the skirt or bearing sleeve oi thelpiston, and the erence character 6 a ring circumierentially secured, preferably by welding, to the inteiorof the skirt or bearing I l, sleeve intermediate itsends. .-Tne skirt or bearing sleeve 5 is preferably made of high carbon steel' and the ring V6' of any suitable material, such ,as steel. There are provided in the skirt or bear- Fig. 5 is an enlarged fragmentary section, taken the openings, 1 in the skirt or bearing sleeve. Ihe body and the skirt or bearing sleeve are secured together by me of the prongs 8 which are embedded in the thickened portion of the The skirt or bearing sleeve 5 may be formed byany suitable process and the ring 6 is preferc 4 ably securedthereto by welding. To complete the piston, the' skirt or bearing sleeve is placed in asuitable mold-preferably a permanent moldand the mold and skirt or bearing sleeve heated to such a temperature that, when the completed piston is cooled to ordinary atmospheric temperadially, as shown in Fig. 5, and that, when the completed piston is at ordinary engine operatingtemperatures, the skirt or bearing sleeve and-the out the body portion exerting sufficient pressure radially against the skirt or bearing lsleeve to ex pand it to-a diameter greater than that whichit would normally assume at that temperature. Afterthefumold and the skirt or bearing sleeve have been heated to the desired temperature, the molten metal of which the body is to be formed,

is'ntroduced into the mold, and thus the body portion is formed and becomes interlocked with the skirt or bearing sleeve-5 by the prongs 8 which become embedded in the metal of the head. By heating theskirt or bearing sleeve 5 to the temperature mentioned above, betoi'e the molten metal of which the body is whe yformed is cast .`thereinto, it isinsuredthat, when the piston is at ordinary engine operating temperatures, there will be no tendencyfor the expansion of the body to affect the expansion of the skirt or bearing sleeve and cause Vbinding of the piston in the cylinder. At lower temperatures, such as those 'being started from operates when the engine is at which the piston the cold, the body will tend 'to withdraw radially from the skirt or bearing sleeve by sliding inwardly on the prongs 8 on the ring 6. The provision of a plurality of these prongs 8, each of which .entersthe body at a different angle, prevents the body and the skirt or bearing sleeve from becoming loose and rattling A under such conditions. Y

- sirable one since it is thereby insured that for no great length of time, while the engine'is operatin g, will the prongs 8 be required to function as connecting means between the head and the skirt or bearing sleeve.

Althoughlhave shown and 'described a preferred embodiment of my invention, it is to be understood that this has been done by way of `example, and not by way of limitation, and that the'scope of my invention is to be determined 6 only byl the appended claim.

f I claim:

In a composite piston, a circumferentially continuous bearing sleeve of wear resisting sheet metal or alloy, a cup shaped body of a light metal l0 or alloy which has a higher temperature coeilicient of expansion than vthe metal or alloy of which the bearing sleeve is made and whose open end extends well into the bearing sleeve, a. ring which is located within the bearing sleeve and l5 secured to it between its ends, and spaced approximately horizontal projections on the ring Y and embedded in the cup shaped body.

'ramon P. 2o 

